Browns cornerback Joe Haden acknowledged he tested positive for the stimulant Adderall, leading to his four-game suspension for violating the NFL's policy on banned substances.

Haden returned to the Browns on Monday for the first time since he was suspended. Haden apologized to Cleveland's fans, his teammates and coaches "for my very dumb mistake." Haden said he "hurt a lot of people for the decision that I made, and I apologize from the bottom of my heart."

Haden said being away from the Browns has been tough. He spent the time reflecting on his life. Haden feels the penalty was excessive but "I've served and honestly want to move forward and play."

The Browns lost all four games while Haden was suspended. At 0-5, they are the league's only winless team heading into this Sunday's game against Cincinnati.